利用IO流做的“随机点名器” - 黑马程序员技术交流社区

package me.zhouyou.io;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Random;
import java.util.Scanner;
public class GetRandomName {
private static BufferedReader br = null;
private static ArrayList<String> al = null;
private static Scanner sc = new Scanner(System.in);
private static Scanner scanner = new Scanner(System.in);
public static void main(String[] args) throws IOException {
System.out.println("********** 欢迎来到随机点名器~ **********");
// 封装数据源
br = new BufferedReader(new FileReader("names.txt"));
// 将名字添加到集合
al = new ArrayList<String>();
String line = null;
while ((line = br.readLine()) != null) {
al.add(line);
}
while (true) {
System.out.println();
System.out.println("******* 请输入数字选择 *******");
System.out.println("* 1，随机点名 ");
System.out.println("* 2，添加名字 ");
System.out.println("* 3，删除名字 ");
System.out.println("* 4，名字列表 ");
System.out.println("* 5，关闭 ");
// 获取用户输入
int number = sc.nextInt();
switch (number) {
case 1:
// 获取随机名
getRandomName();
break;
case 2:
// 添加名字
getName();
break;
case 3:
// 删除名字
printArraylist();
removeAL();
break;
case 4:
// 输出集合
printArraylist();
break;
case 5:
// 关闭
br.close();
sc.close();
scanner.close();
System.exit(0);
break;
default:
System.out.println("输入有误,请输入(1-5)内的数字,如: 1 ");
break;
}
}
}
// 点名方法
public static void getRandomName() throws IOException {
// 获取随机数
Random r = new Random();
int index = r.nextInt(al.size());
System.out.println("随机点名为：" + al.get(index));
}
// 添加名字
private static void getName() throws IOException {
System.out.println("请输入一个要添加的名字：");
String name = scanner.nextLine();
if (al.contains(name)) {
System.out.println(name + ",已经存在！");
} else {
al.add(name);
System.out.println(name + ",成功添加！");
// 将集合中的数据重新写入到文件中
BufferedWriter bw = new BufferedWriter(new FileWriter("names.txt"));
for (String s : al) {
bw.write(s);
bw.newLine();
bw.flush();
}
bw.close();
}
}
// 删除方法
private static void removeAL() throws IOException {
System.out.println("请输入需要删除名字的编号：");
int index = sc.nextInt();
if (index > 0 && index < al.size()) {
System.out.println(al.get(index)+",成功删除！");
al.remove(index);
// 将集合中的数据重新写入到文件中
BufferedWriter bw = new BufferedWriter(new FileWriter("names.txt"));
for (String s : al) {
bw.write(s);
bw.newLine();
bw.flush();
}
bw.close();
} else {
System.out.println("输入有误：输入的编号没有对应的名字");
}
}
// 遍历集合
private static void printArraylist() {
System.out.println("共有如下名字：");
for (int x = 1; x < al.size(); x++) {
System.out.println(x + ":" + "\t" + al.get(x));
}
}
}

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